I can't find any reference to this type except in Orchard 1.4 and we are running 1.3. A default install of orchard using WPI does work so I am pretty sure the server has the necessary dependencies available, and IIS is setup correctly. A log file is
being created but nothing is being written to it.

Server is a brand new windows 2008 R2 with .net 4 and IIS7. App pool is set to 4.0, and integrated mode